1. Field of the Invention
The present invention relates to electrical connectors. More specifically, the present invention relates to modular jack receptacles having an internal filter element.
2. Brief Description of Earlier Developments
Modular jacks are used in two broad categories of signal transmission: analog (voice) and digital (data) transmission. These categories can overlap somewhat since digital systems are used for voice transmission as well. Nevertheless, there is a significant difference in the amount of data transmitted by digital systems. A low speed system ordinarily transmits from about 10 to 16 megabits per second (Mbps), while a high speed system may transmit at 155 Mbps or even higher data rates. Often, high speed installations are based on asynchronous transfer mode transmission and utilize shielded and unshielded twisted pair cables.
With recent increases in the speed of data transmission, requirements have become important for electrical connectors, in particular, with regard to the reduction or elimination of crosstalk. Crosstalk is a phenomena in which apart of the electromagnetic energy transmitted through one of multiple conductors in a connector causes electrical currents in the other conductors. Another problem is common mode electromagnetic interference or noise. Such common mode interference is often most severe in conductors of the same length, when a parasitic signal induced by ESD, lightning or simultaneous switching of semiconductor gates arrives in an adjacent electrical node through multiple conductors at the same time.
Another factor which must be considered is that the telecommunications industry has reached a high degree of standardization in modular jack design. Outlines and contact areas are essentially fixed and have to be interchangeable with other designs. It is, therefore, important that any novel modular jack allow the use of conventional parts or tooling in its production with only minor modification.
U.S. Pat. No. 5,513,065, to Caveney et al., discloses a solution to reduce crosstalk in a modular connector. Caveney et al. propose a multilayer capacitive label that is inserted into a recessed region of a modular jack connector proximate to the contacts within the connector. The label is secured to the contacts using a conductive adhesive that capacitively couples one conductor from a first differential pair with another conductor from a second differential pair. A conductive epoxy is used to make an electrical connection between signal conductors and an electrode of the capacitor. However, the solution proposed by Caveney et al. is limited because the capacitive label must be placed in physical contact with the conductors in the connector. As such, this solution provides sufficient results with differential pairs 3/6 and 4/5, but does not work well for other differential pairs.
While the above provides some reduction in crosstalk under limited circumstances, there still remains a need for improvements in the reduction of crosstalk in modular jack connectors. The present invention provides such a solution.